Motor control system



Jan. 5, 1932. D, Q wRlGHT I 1,840,281

MOTOR CONTROL SYSTEM Filed Sept. 28. 1929 HOISTING' swr'rcuss ZOWERING swrrc a as l .7 10m 23 2514 1s (6 7 :0 1a 25 2514 :5 (6

on a arr s 1 O 0 S 1 o o o o T 2 0 T 2 o o T 0 Q E 3 0 0 E 5 o 0 0 4' 0 o 0 P 4 0 S 5 o 0 o a S 5 o o INVENTOR Patented Jan. 5, 1932 UNITED STATES PATENT OFFICE DAVIDHC. WIt IGHT, OF CLEVELAND, OHIO, ASSIGNOR TO ELECTRIC CONTROLLER &; MANUFACTURING COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO' MOTOR CONTROL SYSTEM.

Application filed September 28, 1929. Serial No. 395,809. R Su U E D My'invention relates to motor control systerns.

It has been the practise in some systems when lowering a load to connect on the first point of the controller the series field winding and the winding for a series brake in series/with one path andto by-pass these windings by the armature and a shunting resistance in another path, these paths being connected in series with a current-limiting resistance. In systems of this type a part only of the current taken from the supply,

line passes through the brake winding, and it is generally necessary to make the shuntmg resistance have a comparatively low value so as to secure a high dynamic braking torque and slow speed on heavy overhauling loads on the first controller point on l0wering,'but this lowering of the shunt resistance allowed less current to pass through the brake winding because more current passed from the line through the armature shunt.

It is one object of this invention to parallel the field winding by the armature and the shunting resistance and to connect a series brake winding and current-limiting *resist ance in series with the parallel paths just described so that all he current taken from the supply line passes through the brake winding and so that the shuntingresistance can be made as low as' required without reducing the amount of current flowing through the brakewinding. With my system the lowor the shunt resistance the higher the current flowing through the brakewinding.

Another object of this invention .is to provide for a motor having its field and armature in shunt during lowering, improved circuits which will give positive driving torque, on non-overhauling loads and dynamic braking torque on overhauling loads. Other ob 'jects will appear hereinafter.

Referring to the accompanying drawings, Fig. 1 shows a diagram of my motor control system. Fig. 2 is a diagram indicating the position of the switches for 'the various controller points or steps during a hoisting operation. Fig. 3 is a similar diagram indicating the position of the switches during a lowering operation.

switch between the line '1 and the armature.

8 is a wire connected between the line 1 and the point 9 between the armature and the field winding. The wire 8 has the switch 10.

The resistance 6 is divided into the sections 11, 12 and 13, controlled by the respectlve switches 14, 15 and 16.

A wire having the switch 18 and the shunting resistance 19 has one end connected to' the point 20 between the armature 3 and the switch 7, and, theother end to the point 21 winding 5.

A wire 22 having the switch 23 is connected adj'ustably at one end to the resistance 6 and at the other end to the resistance 19.

A wire '24 having the switch 25 is connected at one end to the point 26 between the wire 2 and the resistance 6 and at the other end adjustably to the resistance 19.

The switch 18 is in closed position while the controller is in the oil position, as shown by Figs.'2 and 3. I

The operation of the system during the hoisting of a load will now be described, reference being made to Figs. 1 and 2. On the first step as shown in Fig. 2 the switch 7 is closed (the switch 18 remaining closed) which connects the armature, the field and This causes the speed of the motor to increase. The motor speed is further increased on steps 3, 4 and 5 by closin the switches 14;, 15 and 16 successively 'as Wlll be readily understood.

between the field winding 4 and the brake around the armature and the field winding.

To slow down and stop the motor the switches are opened in reverse of the order just described, the switch 18 remaining closed on the off position.

The system during the lowering'of a load will now be described, reference being made to Figs. 1 and 3.

On'step 1 switches 10, and 16 are closed, the switch 18 remainin closed, as shownin Fig. 3. Current from t e supply line 1 flows through the switch 10 to the point 20 where it divides into two branches, one bran'chincluding the field' winding 4 and the other branch the armature 3, the shunting resistmice 19 and the switch 18. The two branches unite at the point 21 from which the entire curent through the motor flows in series through the brake winding 5, the switches 16 and 15and the resistance section 11 to the supply line 2. The current flows in the same direction in the field winding as during the hoisting operation, but in the reverse direction through the armature, so that the armature rotates in the opposite direction from that which it rotated during the hoisting 0 eration. .All the current flowing from the l1ne 1 passes through the brake winding which insures the release of the brake at once. The circuits described provide on the first steplowering a low resistance dynamic braking circuit with high dynamic braking torque for overhauling loads and provides positive driving torque of low value for nonoverhauling loads.

On step 2 the switch 18 is opened and the switch 23 is closed whereby a selected amount of resistance is inserted in the dynamic braking circuit whose right hand point 21 has been moved to a point on the resistance section 11. The insertion of resistance in the dynamic braking circuit causes the dynamic braking torque to be reduced and the speed of overhauling loads to be increased; Also the volta e applied on the armature is increased w ich causes the torque on nonoverhauling loads tobe increased.

On step 3 the switch 16 is opened whereby the resistance section 13 is inserted in the dynamic braking circuit. This weakens the field current so that the speeds ofboth types of loads are increased. I

' Oh step 4 the switch 15 is opened which causes the resistancesection 12 to be inserted -1n the dynamic braking circuit which causes the speeds of both types of loads to increase. On step 5 the switch 23 is opened and the switch 25 is closed. Now the entire resistance 6 is in the dynamic braking circuit, whereby the field is still further weakened and the voltage applied to the armature is increased, so that the speeds of both types of loads are still further increased.

- In moving the controller from the fifth step lowering toward the ofi position, the operation of the switches as shown by Fig. 3

provide the dynamic braking circuits de scribed for reducing the speed of the motor at each successive step until the off position is reached when the armature,the field and the shunting resistance 19 are connected in a dynamic braking circuit with the brake winding de-energized.

I have not shown a controller for controlling the switches in the order and grouping described herein, butengineers skilled in the art to which this invention belongs could easily provide a controller whereby the system as described would be successfully operated.

The foregoing description relates to series wound motors, but this invention is applicable to compound-wound motors, Fig. 1 showing the shunt field winding 27 in addition to the series field windingd.

I claim:

1. For a motor control system for hoists, means for connecting the motor armature and the series field winding in series for hoisting, means for connecting the motor armature and the series field winding in parallel for lowering, a brake winding for the motor and connecting means for causing the value of the current in the brake winding to be equal to the sum of the values of current in the motor armature and field windings when current is first admitted to the motor in lowering.

2. For amotor control system, a motor, a

in gs. '3. For a motor control system, a motor having a'series field wlnding, a series brake winding therefor, a resistance for the motor circuit, means for connecting the motor armature, the series field, the brake winding and the resistance in series for operation in one direction, reversing means for connecting the resistance and the brake winding in series with two parallel paths, one path containing the armature and the other path containing the series field winding for operation in the other direction and connections whereby the said reversing means cause the value of the current in the brake winding to be equal to the sum of the values of current in the motor armature and field windings.

4. 'For a motor control system, a motor having armature and field windings, a brake winding for the motor, a current-limiting reshunted across the motor armature and the iii field windings, means connecting the currentli1niting resistance and the brake winding in series with two parallel paths, one path containing the armature and the field winding of the motor and the other path containing the resistance, and meansfor opening the circuit of the parallel path containing the shunting resistance.

For a motor control system, a motor having armature and field winding-s, a brake winding for the motor, a current-limiting resistance, a shunting resistance "normally shunted across themotor armature and the field winding, means connecting the currentlimiting resistance and the brake winding in series with two parallel paths, one path containing the armature and the field winding of the motor and the other path containing the shunting resistance, means for opening the circuit of the parallel path containing the shunting resistance, and means for varying the current-lin'iiting resistance.

8. Fora motor control system for hoists, a motor having armature and field windings,

, a brake winding, a current-limiting resistance, a shunting resistance, means on first application of power in lowering for connecting the current limiting resistance and the brake winding in series with a branched circuit, one branch containing the motor field and the other branch containing the motor armature and the shunting resistance, a dy namic braking circuit connecting a point on the shunting resistance to a point on the current limiting resistance, means for closing and opening the latter circuit, and means for opening the said branched circuit containing the armature and the shunting resistance.

7. For a motor control system for hoists, a motor having armature and field windings, a brake winding, a current-limiting resistance, a shunting resistance, means on first ap 'ilication of power in lowering for connecting the current-limiting resistance and the brake winding in series with a branched circuit, one branch containing the motor field winding, the other branch containing the motor armature and the shunting resistance, a dynamic braking circuit connecting a point I on the shunting resistance to a point on the current-limitin g resistance, means for closing and opening the latter ,circuit, means, for

opening the said branch circuit containing the armature and shunting resistance, and means for increasing the resistance in the dynamic braking circuit and the voltage ap plied to the terminals of the motor armature.

8. For a motor control system for hoists, a source of supply, a motor having armature and field windings, a current-limiting resistance, a shunting resistance, means for se curing slow speed lowering including a connection from the source of current to the limiting resistance in series. with a branched circuit, one branch containing the motor field and the other branch containing the motor armature and the shunting resistance, means for increasing the loweringspeed, including a dynamic braking circuit connecting a point on the shunting resistance to a point on the current-limiting resistance, means for opening the said branch of the circuit containing the motor armature and the shunting resistance, and means for further increasing the lowering speed including a connection from a point on the shunting resistance to the source of supply and means for opening the said connection between the shunting resistance and the current-limiting resistance,

9. For a motor control system for hoists, a source of supply, a motor having'armature and field windings, a current-limiting resistance, a shunting resistance, means for securing slow speed lowering including a connection from the source to the limiting resistance in series with a branched circuit, one branch containing the motor field and the other branch containing the motor armature and the shunting resistance, means for increasing the lowering speed including a dynamic braking circuit connecting a pointon the shunting resistance to a point on the current-limiting resistance, means for opening the said branched circuit containing the motor armature and the shunting resistance, and means for increasing the dynamic braking resistance and the voltage on the motor armature for further increasing the lowering speed.

10. For a motor control system for hoists, a source of supply, a motor having armature and field windings, a brake winding, a current-limiting resistance, a shunting resistance, a slow speed contact normally closed connecting the armature and field windings in a branched circuit, one branch containing the field winding and the other branch containing the armature and the shunting resistance, intermediate and high speed contacts, current-conducting means including a set of main contacts for connecting the said source to the current-limiting resistance and the brake winding in series with the said branched circuitnneans for closing and opening the intermediate speed contact between a point on the shunting resistance and a point on the current limiting resistance, means for opening the said normally closedslow speed contact, and means for closing the high speed contact between a point on the shunting resistance and the source.

11. For amotor control system for hoists, a source of supply, a motor having armature and field windings, a brake winding, a current-limiting resistance, a shunting resistance, a normally closed slow speed branched circuit, one branch containing the field winding and the other branch containing the armature and the shunting resistance, inter mediate and high speed contacts, current-conducting means including a set of main contacts tor-connecting the said source, the current-limiting resistance and the brake winding in series with the branched circuit, means for connecting the intermediate speed con tact to a point on the shuntingresistance and to a point on the current-limiting resistance, means for opening the said normally closed slow speed contact, means for connecting the high speed contact to a point on the shunting resistance and to the source, and for opening the intermediate speed contact, and means for varying the current-limiting resistance.

12. In a motor control system for hoists, a source of supply, a motor having armature and field windings, a brake winding, a shunting resistance, a current-limiting resistance, a normally closed loop circuit including the motor armature, the field winding and the shunting resistance, means in hoisting for connecting the current-limiting resistance and the brake winding to the source of supply in series with the said loop circuit and for connecting the armature and the field.

windings in parallel with the shunting resistance, and means for opening the loop circuit, in combination with means in lowering for connecting the current-limiting resistance and brake winding to the source in series with the said loop circuit and for connecting the field winding in parallel with the armature and shunting resistance.

13. In a motor control system for hoists,

a source of supply, a motor having armature and field windings, a brake winding, a shunting resistance, a current-limitin resistance, a normally closed loop circuit inc' uding a motor armature, the field winding and the shunting resistance, means in hoisting for connecting the current-limiting resistance and the brake winding to the source of supply in series with the loop circuit and for connecting the armature and the field windings in parallel withthe shunting resistance, and means vfor opening the loop circuit, in combination with means in lowering for conecting the current limit resistance and the brake winding to the source in series with the loop circuit and for connecting the field winding in parallel with the armature and the shunting resistance, speed increasing contacts, and means for closing the said speed increasing contacts to a point on the shunting resistance and to a point on the currentlimiting resistance and means foropening the said loop circuit to obtain a higher lowering speed of the motor. I

14. In a motor control system for hoists, a source of supply, a motor having armature and field windings, a brake finding, a shunting resistance, a current-limiting resistance, a normally closed loop circuit including the motor armature, the field winding. and the shunting resistance, means in hoisting for connecting the current-limiting resistance and brake winding to the source in series with the said loop circuit, and for connecting the armature and field windings in parallel with the shunting resistance, and means for opening the loop circuit, in combination with means in lowering for connecting the current-limiting resistance and the brake winding to the source in series with the said loop circuit and for connecting the field winding in parallel with the armature and shunting resistance, intermediate and high speed contacts, means for closing the intermediate speed contacts to a point on the shunt-ing resistance and to a point on the current-limiting resistance, means for opening the said loop-circuit for obtaining a higher lowering speed of the motor, and means for connecting the high speed contacts to a point on the shunting resistance and to the said source.

115. The method of changing the speed of a hoisting motor while lowering, wherein a current limiting resistance is connected to the supply lines in series with a branched circuit having two parallel paths, one path containing the motor field and the other path containing the motor armature and a shunting resistance, which consists in including a portion of the current limiting resistance in the parallel path containing the field winding and excluding a portion of the shunting resistance from the parallel path containing the motor armature.

16. The method of changing the speedof a hoist motor associated with an electric brake while lowering, wherein a current limiting resistance, the motor brake winding and a branched circuit having two parallel paths are connected in series to the supply lines, one path containing the motor .field and the other containing the motor armature and'a shunting resistance, which consists in including the brake winding in the parallel path containing the motor field and excluding a portion of the said shunting resistance from the parallel path containing the motor armature.

17 The method of changing the speed of a hoisting motor associated with an electric brake while lowering, wherein a currentlimiting resistance is connected to the supply lines in series with two parallel paths, one path containing the motor brake winding and the field winding of the motor and the other parallel path containing the motor armature and a shunting'resistance which consists in includin substantially all of the said current limiting resistance in the parallel path containing the motor brake and field'winding and excluding a portion of the said shunting resistance from the parallel path containing the armature winding.

In testimony whereof, I hereunto afiix my signature.

DAVID C. WRIGHT. 

